The excerpt meta box allows working with the post_excerpt field. By default, is used only in posts and attachments.
Interface
add_post_type_support
By the Web Warlock, Wednesday, 28/Jul/2010 4:43
<?php add_post_type_support( $post_type, $feature ) ?>
excerpt post type feature
By the Web Warlock, Wednesday, 28/Jul/2010 3:51
The excerpt
post type feature indicates whether the excerpt meta box will be displayed in the edit post screen.
Adding excerpts to Pages
By the Web Warlock, Wednesday, 28/Jul/2010 3:47
To add excerpts to Pages, from 3.0 on you just need to add the support for the excerpt
feature for the page
post type with add_post_type_support called in the init
hook.